The prior art is replete with examples of the application of carbon in various forms to magnetic media, etc. for the purpose of providing wear resistance and/or lubricity. Representative of such prior art disclosures are the following:
______________________________________ PATENT # INVENTOR ASSIGNEE ______________________________________ RE 32,464 Aine (1987) 2,804,401 B. A. Cousino (1957) 4,060,660 Carlson et al RCA Corporation (1977) 4,277,540 Aine (1981) 4,411,963 Aine (1983) 4,486,286 Lewin et al Nerken Research Corp. (1984) and Technion Research & Development Foundation, Ltd. 4,495,242 Arai et al Fuji Photo Film Co., (1985) Ltd. 4,524,106 Flasck Energy Conversion (1985) Devices, Inc. 4,552,820 Lin et al Lin Data Corporation (1985) 4,598,017 Bayer et al International (1986) Business Machines Corporation 4,647,494 Meyerson et al International (1987) Business Machines Corporation 4,661,409 Kieser et al Leybold-Heraeus GmbH (1987) 4,664,976 Kimura et al Victor Company of (1987) Japan, Ltd. 4,713,279 Fujiwara et al Fuji Electric Co., (1987) Ltd. 4,713,288 Kokaku et al Hitachi, Ltd. (1987) 4,717,622 Kurokawa et al Matsushita Electric (1988) Industrial Co., Ltd. 4,725,470 Katsuki Alps Electric Co., (1988) Ltd. 4,737,419 Hilden et al International (1988) Business Machines Corporation 4,755,426 Kokai et al Hitachi Maxell, Ltd. (1988) 4,774,130 Endo et al Hitachi Metals, Ltd. (1988) 4,786,564 Chen et al Komag, Inc. (1988) 4,789,598 Howard et al International (1988) Business Machines Corporation 4,794,047 Funamoto Hitachi, Ltd. (1988) 4,804,590 Nakamura et al Nihon Shinku Gijutsu (1989) Kabushiki Kaisha 4,816,334 Yokoyama et al TDK Corporation (1989) 4,818,608 Furuyama Matsushita Electric (1989) Industrial Co., Ltd. 4,820,584 Morita et al Kabushiki Kaisha (1989) Toshiba 4,839,244 Tsukamoto NEC Corporation (1989) 4,861,662 Kobliska et al Akashic Memories (1989) Corporation ______________________________________
It is to be noted that practitioners in the art have heretofore recognized the desirability of providing an adhesion enhancing, intermediate layer between the carbon overcoating and magnetic media of the type found in recording disks. Such prior art teachings include the following:
______________________________________ PATENT # INVENTOR INTERMEDIATE LAYER ______________________________________ 4,503,125 Nelson et al Titanium (1985) 4,647,494 Meyerson et al Silicon (1987) 4,661,409 Kieser et al Siloxanes, Silazanes, (1987) Polymers 4,713,279 Fujiwara et al Silicon Oxide (1987) 4,713,288 Kokaku et al Organic (1987) 4,737,419 Hilden et al Organic Binder of (1988) Magnetic Layer ______________________________________
In the three United States Aine patents noted in the first compilation above, i.e., U.S. Pat. Nos. 4,277,540, 4,411,963 and U.S. Pat. No. Re. 32,464 there is specific reference made to the use of magnetic transducer head portions, which come into contact with recording media, being preferably formed of or coated with carbon.
The prior art disclosures notwithstanding, and even though patents such as those set forth in the second compilation above provide what appear to be insulating intermediate layers between magnetic media and carbon overcoating, such art totally fails to suggest or disclose the unique concept of the present invention. This unique concept is characterized by the provision of a protective wear coating such as carbon on a magnetic transducer head of the type used in magnetic recording where an insulating or substantially non-conductive, adhesion enhancing intermediate layer is provided between the carbon overcoating and the protected head surfaces. This insulating layer prevents electrical short circuiting or conductivity between spaced head portions which must retain distinct characteristics in order to be effective. These portions may comprise spaced contacts, spaced pole pieces, and or spaced head coil winding elements.
In this manner, degradation of the recording/reading capabilities of the head is prevented while achieving the distinct advantages of enhancing the adhesion of the protective overcoating to the head.
It is recognized that in the prior art it has been suggested, for example in Bajorek et al U.S. Pat. No. 4,918,554, that a shielded magnetostrictive sensor may be fabricated with alternating layers of insulating and conductive material with appropriate heat treating of these layers being required.
This technique is specifically disclosed as being intended to avoid the problems due to scratching or smearing during use of the unit which could create short circuit conducting pads between the leading shield and sensor layers, thereby resulting in sensor shorting. This wholly distinct concept involves considerations distinct from those of the present invention which relate to the application of a protective wear resistant overcoating to a magnetic head through a technique which prevents degradation of the magnetic properties of the head during the application of the wear resistant coating itself. In this way, the gap between spaced head or pole segments, head coil windings, and/or head coil contacts is prevented from being occupied by conductive wear resistant material, such as carbon, through the prior, intervening application of a non-conductive or insulating, adhesion promoting layer.